The rotating portion of an electric motor has angular momentum and kinetic energy during the motor's operation. Since both angular momentum and energy must be conserved, the rotating portion of the motor will continue to rotate until the angular momentum is transferred to other objects and the energy is dissipated. However, for a variety of applications using electric motors, it is advantageous to bring a motor, including its rotating shaft, to a prompt stop rather than allowing it to coast to a stop. Toothed electromagnetic clutch brakes are often employed for this purpose. A toothed electromagnetic clutch brake is a motor stopping device that utilizes a toothed electromagnetic clutch to transfer the motor's angular momentum and energy to an armature assembly that is sufficiently secured to a fixed structure to promptly stop the shaft's rotation.
Toothed electromagnetic clutches transmit angular momentum and energy through the use of interlocking teeth. In general, toothed electromagnetic clutches are comprised of an armature assembly, a rotor, and a coil. The rotor is coupled to a shaft that is driven by an electric motor or other similar device such that the rotor rotates with the shaft. The armature assembly may be enabled to rotate about the same axis as the rotor ring. Additionally, the armature assembly and the rotor possess mutually interlocking teeth. Further, the toothed portions of the armature assembly and the rotor are capable of relative axial movement such that when the coil is energized to create a magnetic field the toothed portions of the armature assembly and the rotor to come together. When the armature assembly and rotor come together, their teeth interlock causing the rotor to apply torque to the armature assembly. The application of this torque transmits energy and angular momentum from the rotor to the armature assembly. During engagement, which is when the toothed portions of the armature assembly and the rotor come together, toothed electromagnetic clutches unfailingly allow the rotor to apply compact, high torque to the armature assembly without the occurrence of slippage. During disengagement, toothed electromagnetic clutches unfailingly prevent the application of torque without the occurrence of entanglement.
A toothed electromagnetic clutch brake is a motor stopping device that utilizes an electromagnetic clutch to transfer the angular momentum and kinetic energy associated with a de-energized electric motor to an armature assembly that is sufficiently secured to a fixed structure to promptly stop the shaft's rotation.
In prior art toothed electromagnetic clutches, the toothed portion of the armature assembly (“the armature”) and the toothed portion of the rotor (“the rotor ring”) are either machined, or they are manufactured by powder metallurgical methods using sintered metal. Both of these methods have problems associated with them.
Machining of armatures and rotor rings, which is usually accomplished through the use of a one-reed hob, milling cutter, involute pinion cutter, or the like, is a time intensive and resultantly expensive process, since numerous processes are required to form the tooth flanks. Additionally, it is difficult to guarantee the dividing accuracy of the interlocking teeth and machining defects tend to occur. These problems are magnified when the number of interlocking teeth is large.
Manufacturing armatures and rotor rings through the use of powder metallurgical methods is less expensive and time consuming than machining them. However, the resulting materials are not as tough as the machined armatures and rotor rings, and it is difficult to guarantee the mechanical strength of the teeth. Moreover there is a major impact on product life and manufacturing cost due to the density and durability of the materials.